Oracle Objects and using dot notation

I'm trying to understand how to use objects in Oracle and curious why the following example doesn't work.  Or what is missing that would make it work using Objects and dot notation.

create table comments_table
(dat date,
 comments varchar2(200));

declare
  type ser_table is table of varchar2(10) index by binary_integer;
  ser_list   ser_table;
  temp_count integer := 0;
begin
  ser_list(1) := 'TEST 1';
  ser_list(2) := 'TEST 2';
  ser_list(3) := 'TEST 3';

  -- Doesn't work
  insert into comments_table(dat,comments) values(sysdate,ser_list.count||' records inserted.');

  -- Does work
  temp_count := ser_list.count;
  insert into comments_table(dat,comments) values(sysdate,temp_count||' records inserted.');

end;